With plenty of natural-gas pipelines in New Jersey and more on the way, lawmakers want to reduce leaks in those systems, which can pose a safety hazard to the community while increasing pollution contributing to climate change.

In its first meeting of the new legislative session, the Assembly Telecommunications and Utilities Committee approved a bill, A-436, that would require natural-gas utilities to repair or replace pipelines that leak gas within timeframes to be established by the state Department of Environmental Protection or face fines.

The legislation, opposed by a utility trade association as potentially conflicting with existing safety regulations, is being considered at a time when about 15 new natural gas pipelines have been proposed or are under consideration in the state, spurring protests from local communities and environmentalists. The expansion reflects policies adopted by the Christie administration amid plentiful supplies of the fuel, which have lowered heating bills for consumers.

A mounting area of concern among opponents is leakage from the vast network of thousands of miles of pipeline, including methane -- a potent greenhouse gas that helps cause global warming. Methane, the primary component of natural gas, accounts for nine percent of all U.S. greenhouse-gas emissions from human activities, making it the second most prevalent source of global warming after carbon dioxide.

“Most state and federal laws and regulations pertaining to natural-gas pipelines focus primarily on health and safety issues, but not the environment,’’ said Assemblyman Tim Eustace (D-Bergen), the bill’s sponsor. “This bill would address the climate-change impacts from natural-gas pipeline leaks by requiring gas utilities to repair or replace leaking pipelines in a timely fashion.’’

But the state’s gas utilities already are addressing that issue, said Thomas Churchelow, senior director of government and public affairs for the New Jersey Utilities Association. He suggested the bill could lead to conflicting regulations that conflict with existing state and federal requirements.

Under the bill, the DEP in consultation with the state Board of Public Utilities would be required to adopt regulations establishing inspection and reporting requirements, prioritized timeframes for the repair and replacement of pipelines based on the severity of the leaks, best practices, and repair standards.

How effective utilities are in preventing methane from leaking from pipelines is a continuing source of debate. Some studies have show the industry has reduced leaks to a great extent, according to Churchelow.

The underlying policy of fixing leaks from pipelines is being accomplished through an accelerated infrastructure program to replace old cast-iron pipes being undertaken by the four utilities, he said.

For example, Public Service Electric & Gas won approval last November for $905 million to replace 510 miles of its aging gas infrastructure over three years. Those pipelines include cast-iron mains, the chief source of greenhouse-gas emissions in the sector.

Under a partnership with the Environmental Defense Fund and Google Earth Outreach, the utility is taking advantage of the unique mapping initiative to identify and confirm methane leaks using data collected from a Google Street View car.

Joseph Forline, vice president of gas operations for PSE&G, said safety is the top priority in identifying what pipelines should be replaced, but noted about 10 percent of the system scheduled to be replaced this year was prioritized from methane data collected by EDF and the utility.

“We’re aware of the impacts of methane emissions,’’ Forline said. Replacing the cast iron or unprotected steel pipelines with plastic piping that is less brittle will prevent those leaks, he added.